Process of producing n-dihydro-1,2,2&#39;,1&#39;-anthraquinone azine



March 19, 1935. F. w. PECK ET'AL 1,994,484

PROCESS OF PRODUCING.N-DIHYDRQ1,2,2' 1'-ANTHRAQUINONE AZINE Filed March27, 1954 REDUCING AGENT IMPUKE FILTRATE IMPUKITIES INVENTORS FerdinandW. Peck Franc/5 Know/es BY KKW/ ATTORNEY.

Patente Mar. 19, 1935 1394334 ROCESS OF raonucnvo N-DIHYDRO- 1,2,2",l ANTHRAQUINNE AZINE Ferdinand W. Peck, Pennsgrove, N. .J., and

Francis Knowles, Wilmington, Del.,,-assignors to. E. I. (in Bont deNemours .& Company, .Wilmington, Del a corporation of DelawareApplication March z I -CIaims;

This invention relates! to 'N-dihydro l,2,2',,l- ,anthraquinone azine,anda procession the production thereof. p, f

In .1901 Bohn disclosedin U. "S. Patent-No.

5 682,523 that by melting beta-amino-anthraquinone with caustic potashat a temperature of C. to 300? C'., a substance was formed which, onoxidation by blowing in yielded an insoluble blue-vat dye. Bohn laterdiscovered that this original dye was a mixture of two rather closelyrelated compounds, now usually designated as the A and B-isomers.TheA-isomer, N-dihydro- 1,2,2,l-anthraquinone .azinepr indanthrone, isvery valuable commercially. The 'e-iscmer has practically no commercialvalue.

The preparation of the e-iso rner'has been the subject of muchinvestigation and many refinements of the original Bohn process havebeen proposed, particularly with regard to the use of various oxidizingand fiuxing agents in the caustic alkali fusion. On account .of the factthat the fusion meltcontains not only the A-and B-isorners but, also,alizarines and other impurities, one of the more difiicult problems hasbeen the separation or the A-isomer in suitable purity and yields. L

Two methods of separation may be mentioned.

The first of these isdescribed by Bohn in U. S.

Patent No. 724,789. This consists drowning the fusion melt in water,blowing air through the solution, separating the insoluble dye, materialwhich is substantially a mixture of the A- and B-isomers, and thenvatting with sodium hydrosulfite in fresh caustic alkalisolution. Theleuco salt of the A-isomer, being lesssolublethan that of the B-isomerin the presenceof the sodium hynrosulfite, may be separated and theseparated salt oxidized to the dye. It will benoted that this differencein solubility ,of the leuco salts of the A- and B-isomers in thepresence of sodium hydrosulfite is distinctly 'a teaching of Bohn Avariation has been proposed by Rogers, U. S. Patent No. 1,6'79,230. Thisdiffers fromBohns method inrthatthe step of oxidizing the drowned fusionmelt to precipitate the mixture of A and B-dyes is omitted. That is tosay, Rogers dissolves the fusion melt in water, adds, sodiumhydrosulfite and crystallizes the less soluble leuco salt of theA-isomer. In other words, Rogers uses as a vattingmedium thecausticliquor produced when the fusion is drowned. A-fterrseparating theA-isomer leuco salt from the wbyeproducts, it is then oxidized to thedye in any suitable manner. Y

By both of these methods it: will be noted that the final separationof-theleuco salt of the A 1934., Serial No. "717,636

Rogers process, not only the B-isomer leuco salt but alizarines andother" impurities from the caustic fusion are present. The presence ofsuch impurities tends to .increase the difiiculty of sepa-- ration anddecrease the purity of the product.

' It is an object of the present invention to provideanew and improvedprocess for the production of N-dihydr'o-LZ ,2 ,1-anthraquinone azine ina high stateof purity. Another object is to provide a new and improvedmethod of producing Nrd hyfiro-lflfl,1"-anthraquinone azinein highyields. Other objects will appear hereinafter.

1 These objects'are accomplished according to the present invention bythe combination of steps .involvingfusing betaamino anthraquinone withmolten caustic alkali; mixing the fusion mass with water, separating the,crude A-isomer leuco salt, clarifying the residual caustic alkalisolution by removalof the B-isomer and alizarines, then mixing the crudeA-isomer leuco salt previously separated with the clarified causticalkali solution, adding sodium hydrosulfite, crystallizingtheleuco saltof then-isomer; and isolating it, 'e'. .g., by filtration.",Uponlox'idationof the leuco salt' thus produced, 'Ndihydro-'1j,2,2';1' anthraquinone azine is obtained.

By effecting a preliminarylseparation oi the A-isomerleuco salt andthen.subjecting it to treatment with sodium hydrosulfite in the sub stantialabsence of contaminating impurities such as the B -isomer leuco salt andali arinesQa product of excellent purity is obtained.

The accompanying flow-sheet illustrates in more detail how. theinvention may be practised.

A specific, methodof operation described in con- 'riec'tion with theflow-sheet, but Without statingproportions of materials, is as follows:

The fusion of beta-amino-anthraquinone is carried out in vessel '1 witha mixture of sodium hydroxide and potassium hydroxide in the presence ofan oxidizing agent such as,'for example,

potassium chlorate, and also in the presence of l so-called fluxi'ngagents such' as, for example, sodium acetate and sodium phenolate, theuse of which gives an increased yield of A-isorner. This fusion melt isdrowned in warm water in vessel .2 v whereupon, the crude leuco sodiumsalt of the A-is'omejr; crystallizes in coarse needles. This A-iso'merleucosalt, with a small amount of B-isomer leuco salt. and otherimpurities, is isolated from the caustic alkali mother liquor byfiltration in filter press 3. The filtrate, which contains most of theB-isomer as well as various .alizarine bodies which are formed in theyfusion, is run into vessel 4 and aerated to precipitate .the B-isomerand then treated with calcium hyidroxi'de to precipitate thealizarinesjThis caus- The invention will be further understood, but

is. not limited, by the following examples, in which theparts are byweight.

Example I Heat a mixture of 380 parts of potassium hydroxide and 160parts of sodium'hydroxide to 260C. to 275 C. in an agitated iron fusionpot.

When completely fused and mixed, cool and add parts of anhydrous sodiumacetate, 24 parts of potassium chlorate and allow it to mix incompletely. Then adda mixture of 120 parts of betaamino-anthraquinoneand 50 parts of anhydrous sodium phenolate at about 200 C.

When the fusion is complete, drown slowly in 7800 parts of water. Washout the fusion pot, adding. the washings to the drowned charge andfinally adjusting the volume to 12,000 parts. Cool to 40 C. with slowagitation'and filter, saving the filtrate and crude filter cakecomprising substantially the leuco salt of the Arisomer.

Aerate the filtrate until there is no more precipitation of B-isomer.Add150 parts of calcium hydroxide and stir for one hour, testing to seewhether the addition of more lime will precipitate additionalalizarines. After the addition of sufficient lime, filter the causticliquor, discarding the insoluble sludge. I Mix the crude filter cakeobtained as above described into the clarified caustic liquor and heatto 58 C. Add 60 parts of sodium hydrosulfite and stir for fifteenminutes. Examine a sample to determine the size of the crystals andtheir freedom from impurities. Cool to 38 C. and filter, Washing thesodium leuco A-isomer crystals with 3000 to 4000 parts of watercontaining 2% of caustic soda and 0.1% of sodium hydrosulfite.

Continue the washinguntil the filtrate is clear. When completely washed,add the leuco cake to 5000 parts of boiling water and aerate until thereis no change in the form of the crystals. Filter and wash alkali-free;any trace, of blue color from this filtration or washing indicatesincomplete oxidation.

Excellent yields of N-dihydro-l,2,2',1-anthraquinone azine are obtained.The product contains practically no B- isomer.

.' Example II Heat a mixture of 356 parts of potassium hydroxide and 184parts of sodium hydroxide to 275 C. in an agitated iron fusion vessel.When commass slowly in 7800. parts of water, whichis at 40 C. at thestart. Wash out the fusion pot, adding the washings to the drownedcharge, fi-

'hydro-1,2,2',1'-anthraquinone azine sulfite. leuco crystals. Cool thecharge slowly to 25 C. at 42 C. to 45 C. leuco N-dihydr0-1,2,2,1'-an-0.1% of sodium hydrosulfite. w washed, oxidize the crystals to the dyebyboiling illustrated in the examples.

potassium hydroxide alone.

nally adjusting the volume to about-8800 parts. Cool the charge to 35C., stirring-slowly, and at this temperature filter the crude leucoA-isomer crystals, saving the filtrate for purification.

Suspend the crude leuco A-isomer crystals in the caustic liquid, whichhas been purified as in' Example I, to .remove B-isomer and alizarines.When the filter cake is completely broken up, heat to'58 C. and add 60parts of sodium hydrosulfite. After stirring fifteen minutes, examine asample of the charge to determine the size and purity of the leucoA-isomer crystals. Cool to 38 C. and filter, washing the crystals with3000 to 4000 parts of a 2% solution of caustic soda containing 0.1% ofsodium hydrosulfite. When completely washed, oxidize the crystals toN-clithe product as in Example I.

The dye is of excellent-purity.

' Example III Heat 540 parts of potassium hydroxide to 275 C. ,in anagitated iron fusion pot. When melted, cool and add 40 parts ofanhydrous sodium acetate followed by 24parts of potassium chlorate,

and allow it to mix completely. At200 C. to 205 C. adda mixture of 120parts of beta-aminoanthraquinone and parts of anhydrous sodiumphenolate.

When the fusion is complete, drown the fusion mass in 7800 parts ofwater at 40C., washing out the pot with parts. 7

Cool the charge to 30 C. and filter off the impure leuco A-isomercrystals, saving the'filtrate for purification. Suspend these crystalsin the causticliquor' which has been purified as in Example I, and heatto C. These crystals are normally completely dissolved at this tempera'ture,-with the possible exception of a small amount oxidized in thetransferring of this maand isolate additional water to'make 9800"terial. At 60 C. add 60 parts of sodium hydro- This does not normallyprecipitate any thraquinone azine-potassium salt crystals separate.Filter the crystals'at 25 C. and wash with a cold 2% solution of causticsoda containing When completely in water, washing.

The purity of the color is excellent. The method of effecting thecaustic, alkali fu- Isolate the color by filtrationand sion of thebeta-amino-anthraquinone may vary widely in details well known to thoseskilled in the art. For example, other types of fiuxing agents andoxidizing agents may be used.

Varying proportions of caustic alkali and different temperatures may beemployed than those It is preferable, however, for the purpose of thepresent invention that the fusionbe conducted with a mixture ofpotassium and sodium hydroxides rather than The separation of theA-isomer substantially as its leuco sodium salt leads to a better andmore efficient recovery than the sep'aration as the potassium salt.

Furthermore, in a fusion using potassium hydroxide alone, a temperatureof 5 C. to 10 C.

higher than that ordinarily used with mixtures of potassium hydroxideand sodium hydroxide is normally required. The low-meltingeutecticofpotassium hydroxide and sodium hydroxide is at about 50% potassiumhydroxide, this being inassassin r the caustic fusion mass is added uponcompletion of the reaction is rather important because these factorsfacilitate theseparation' of the A isomer 'leuco salt. According to theRogers patent, previously mentioned, the causticalkali fusion was madewith potassium hydroxide and muchstress was laid upon the tactthat thefusion melt was entirely dissolved in water. 'Moreoveig' according tothe Rogersprocess,crystallization'ofthe leuco salt of the A-iso-m'erinrelativeiy pure torm was only possible by carrying it out in thepresence of sodium hydrosulfite which serves to keep the B-isomerand-other impurities in' solution. Although Brohn pointed ou-tzS. PatentNo.

. 682,523 that the leuco compounds of the A- and B-dyes were presentinthe "caustic. fusion melt, it hasinot heretofore been'consideredpossible to separate the A-isomer leuco salt directly from thedrownedafusion melt in relatively: pure form without an addition agentsuch as sodium hydrosulfite.

This primary isolation of the .leucosalt of the .A-isomer may beeffected by the 263,135- tic alkali fusion in warmrwater (thatismwaterat a temperature 'of about 40 Grystals of the leuco salt of the A-isomerin the form of coarse needles are obtained in relatiyelypureflor'm andmay be easily filtered. Under the preferred conditions of drowning, 'thetemperature normally rises so that at the end of the drowning it isabout58 C. to60 (I. .Only a small amount of cooling is necessary whenfiltering the crude leuco sodium salt crystals; that ispthelcharigej-may:be

cooled from 60 C. to 45 C. without any appreci.

able loss of good color. Blow stirring and cooling seem to precipitateadditional impurities." Especially desirable results are obtaincd'whenthe caustic alkali fusion has been made with a mixture of potassiumand sodiumihydrox-ides, such as previomly described, in which case theleuco crystals are those of the sodium salt. It has been found that veryadvantageous, results are, obtained when the concentration-cf thedrowned fusion mass corresponds to about :5. of caustic alkali. Higherconcentrations;pause-the separation of moremimpurities, maleethefiltration.

more difiicult, and shorten the life of the filter cloth. Lowerconcentrations tend to dissolve more-of the A-isomer .leuco salt andrender the separation more difficult. A

The clarification .of. the caustic .alkaiiliquor from which the crude.leuco salt-of the A-i-somer has been separated isnot limited tothe'exact procedure described in the examples. The Lair-oxidationprecipitates the B isomeri Other methods of oxidation may be used.:Thecxidation may not be essential, however, since the leucoB-isomer maybe precipitated as an insoluble salt along with the aliza-rines, forexample, as the calcium salt by the addition of lime, Whilethealizarines are preferably precipitated'by limeflas'the insolublecalcium salts-they may be precipitated as other insoluble salts :(forexample, the barium or magnesium salts). The treatment with the reagentadapted to precipitatethe insoluble salts may be carried out with orwithout heating, depending upon the specific reagent. Theamount of theprecipitating reagent should be sufiicient to precipitate all ofthematter whichwill form an insoluble salt.

' Whilethe examples describethe oxidation of the A-isomer leuco salt tothe'dye-by boiling in water, it will be recognized that any suitable.method may be employed; By varying the oxidizing agent and theoxidizing conditions, the purity of the color is only slightly afiectedbut' there is a marked difference in its physical state.

The advantages .of 'the present invention will be apparent. Whereasthepriorart process of Bohn involves the final separation of then-isomerleuco salt in the presence ofsubstantially all of the vl3-isomer 'leucosalt and the Rogers process is characterized by thefact that thefinalseparation of the A-isomer leuco'salt is made not onlyin the presence ofthe lit-isomer. leuco salt but, .also,*the alizarines and other.impurities, in the present process substantially all of the B- isomerleuco salt'an'd all of the alizarines are removed from the causticalkali solution prior to the final purification of the A-isomer. The pu-:rified caustic from a previous drowning or fresh caustic may-be "usedfor the final purification of the leuco .A-isomer where conditions orconveni-ence, for example, cost and equipment, permit. The resultantproduct is of a'higher quality than may be obtained by either of theabovenoted .prior art processes. Furthermore, the amount ofsodiumihydrosulfiterequired in the present processsisr less than in theprior art processes. r 1 i n .As many apparently. widely differentembodimentsof this invention may .be made without departing from thespirit and scope thereof, it is to be understoodthat we do notlim'itourselve's to the specific embodiments thereof except as definedin-thefollowing claims.

We claim:

,1. In aprocess ofproducingl T-clihydro-1,2,2',1

anthra u-inone azineinvolving subjecting betav amino-anthra uinone tothe-action of molten caustic alkali whereby a fused reaction mass isobtained, the steps which comprise mixing said .tfusedmass withwaten'separating the crude leuco salt oft-he A-fisomer, introducing theresultant crude .leuco salt of the A-isomer into a-relat'ively purecaustic alkali solution with the addition of sodium hydrosulfite,:andcrystallizing the puriifiedileuco salt of theA-isomer. r T,

. 2. 'Inaprocess'of producing-N+dihyd .anthraquinone azine, the stepswhich comprise subjecting beta-amino-anthraouinone to the action ofmolten caustic alkali wherein a fused reaction mass is obtained, mixingsaid fused mass with water, separating the crude leuco salt of theA-isomer, clarifying the residual caustic alkali solution byremoval ofthe B-isomer and alizar in-es; mixing together the clarified solutionand the crude leuco salt ofthe A-isomer with the addition of sodiumhydrosulfite, and crystallizng thepurifiedleuco salt of the A-isomer.

r '3. In a processof producing N-dihydro-1,2,2 ,1-

anthraquinone azine involving subjecting betaamino a'nthraqui none tothe. action of molten caustic alkali whereby a fused reaction mass isobtained, the steps which comprisemixing said fused mass with water,andseparating A-isomer leuco salt crystals from the drowned fusion meltwithout the addition of a reducing agent.

4. The process of claim 3 in which the fused 'mass is mixed with waterin such amount that the concentration does not exceed about 5.5%. l 5.The process of claim 3 in which the initial heating a mixture of 356temperature of the water to which the-caustic alkali fusion mass isadded is about 40 C.

6.111 the process of producing N-dihydro-1,2, 2,l-anthraquinone azine,the stepswhich comprise subjecting beta-amino-arithraquinone to theaction of molten caustic alkali wherein a fused reaction mass isobtained, adding said fusion mass to water initially having atemperature of about 40 C. and of 'such .amount that'the finalconcentration of the caustic alkali is about'5'.'5%,

separating the :crude leucosalt of the A-isomer,

clarifying the residual caustic alkali solution. by

removal of the B-isomer and alizarines,= mixing together. the clarifiedsolutionand the crude leuco salt of the A-isomer with the addition ofsodium hydrosulfite, and crystallizing the purified leuco saltof theA-isomer.

7. In a process, of producing N-dihydro-1,2,2', 1'-anthraquinone azine,the steps which comprise subjecting beta-amino-anthraquinone totheaction' of molten caustic alkali wherein a fused reaction mass isobtained, mixing said fused mass with water, separating the crude leucosalt of the A-isomer, subjectingethe residual caustic alkali solution toan oxidation. and liming treatment, separating the insoluble sludge,mixing together the resultant clarified caustic alkali solution and.kali concentration isv not more than about 5.5%,

separating theicrude leucosalt of theA-isomer, clarifying the residualcaustic alkali solution by removal of the B-isomer and-.alizarines,mixing together the clarified solution and the crude leuco salt of theA-isomer with the addition of sodium hydrosulfite, and crystallizing thepurified'leuco' salt of the A-isomer. e l

9. In a process ofproducing N-dihydrol,2,2,1-anthraquinone azine, thesteps which comprise subjecting beta-amino-anthraquinone to the actionof a mixture of potassium and sodium hydroxides containing to 80% potas-,sium hydroxide in the presence of potassium chlorate, sodium acetateand sodium phenolate wherein a fused reaction mass is obtained, mixingsaid fused mass with Water initially having a temperature of about 40 C.and in such amount that the final caustic alkali concentration is about5.5%, separatingthe crudeleucosalt of theiA- tion by removal of theB-isomer and ali'zarines, mixing together theclarified solution and thecrude leuco salt of the A-isomer with the addition of sodiumhydrosulfite, and crystallizing the purified leuco salt of theA-isor'nerr 10. The process of producingN-dihydrol,2,2',l'-anthraquinone azine which comprises parts ofpotassium hydroxide' and 184 parts of sodiumhydroxide to as coarsecrystals. I -12."In awprojcess 0f I 1,2,2,1'-anthraquinone" azineinvolving: subject- 'ter in such amount and 'at such v --temperatu'rerises' to about C. isomer, clarifying the residual caustic alkali solu-24 parts of j potassium chlorate, adjusting; the

temperature to about 200 C., and. adding 120;; parts ofbeta-amino-anthraquinone and 50 parts of anhydrous sodium phenolate atabout 200 C.

to about '205-;C.,- after completion of the fusion drowningthe fusionmass slowly in 7800 ;parts of water havingian initial temperature of 4 0(3., f

adjustingthe volume to an alkali concentration ofapproximately 5.5%,coolingthe charge to 35 0., filtering the, impure; leuco A-isomercrystals, :aerating the filtrate, until no, moreprecipitation of theB-isomer occurs, .adding calcium 2 hydroxidetmthe filtrate until nofurtherv precipitation of organic compounds occurs, separate ingthevinsoluble sludge fromthe filtrate, sus V the clarified: filtrate,heating; the suspension to about 58i Ci -adding about 60 parts-Jof'sodiumhypending the impure leuco .A-isomer crystals in j drosulfite,coolingto v38 0., filtering theleuco .A-isome'r crystals, washingthem,and oxidizing them to;

N-dihydro-sl,'2,2f,'1feanthraquinone azine. v

' 11. a -process of N-dihydro- 1,2,2,1-anthraquinonezxazine" involvingsubjectbeta-amino-anthraquinone to 'molten caustic alkali wherein'afused reaction mass'is obtained the step'which comprisesmixing saidfused mass With PIEViOLISIY heated water, whereby the formed A-isomerleuco salt may be-separated ing beta-amino-anthraquinone to the actionof molten caustic alkali whereby a fused reaction mass is obtained, thestep which comprises'mixing said-fused mass with previously heated waterinsufiicient in amount to dissolve the fusion mass;

whereby the A-isomer leuco salt is formeddi rectly as coarse crystals.

ing betaf'amino anthraquinone to 'the'action of molten caustic "alkaliwhereby a fused" reaction mass is obtained, the step which comprisesmixing said fused mass with water at an initial'temperature of about 40"C.,' the amount of water' being insufiicient'to dissolve the "fusionmass and 1 the final caustic alkali concentration beingfnot more thanabout 5.5%. Y

14-. In a process of producing N-dihydrol,2,2',l'-anth'raquinone azineinvolving subject'- ing beta-amino-anthraquinone to the action of 13;Ina" process of producing N-dihydro- '1,2,2',1' -anthraquinone-' azineinvolving subjectmolten caustic alkali whereby a fused reaction mass isobtained, the step which comprises'mixing said fused mass with"previously heated-waa =rate that'the 15. The process of :claim 11 inwhich the caustic alkali is a mixture of potassium and sodium hydroxidescontaining 50%. to potassium. hydroxide. t

16. The process of claim 12 in which the caustic alkali isa mixtureofpotassium and sodium hydroxidescontaining 50% to 80% potassium ydroxide.'I I FERDINAND'W. PECK,

, FRANCISKNOWLES.

